Traffic signals are located on roadways throughout the world to control the flow of traffic through intersections and other areas. A typical traffic signal includes three phases—a red phase, a green phase, and a yellow or amber phase. A red traffic signal typically indicates that traffic facing the traffic signal should stop and not enter the intersection. A green traffic signal typically indicates that traffic facing the traffic signal is free to pass through the intersection. An amber or yellow traffic signal provides a warning that the traffic signal is soon going to turn red.
A typical driver spends significant time idling in traffic. A lot of this time is spent idling behind traffic signals. To address this situation, advanced traffic signal control methods such as traffic-actuated signals and signal synchronization have been utilized. However, these control methods are typically very costly to implement and maintain. Even with these control methods in place, drivers typically cruise at full speed toward a green traffic signal and have to come to a sudden halt whenever the traffic signal turns red. This increases fuel use, engine and brake wear, and sometimes trip time. If traffic signal timing and position are known, the velocity (speed) of a vehicle can be planned through the traffic signals to reduce idle time at red. This can lead to lower fuel use, emissions, engine and brake wear, and in certain circumstances reduced trip time.
Intelligent traffic signal systems that transmit the future state of traffic signals to vehicles are known. For instance, researchers are now experimenting with transmitting the future state of traffic signals to vehicles within the Cooperative Intersection Collision Avoidance Systems (CICAS) initiative. R. Sengupta, S. Rezaei, S. Shladover, D. Cody, S. Dickey, and H. Krishnan, “Cooperative collision warning systems: Concept definition and experimental implementation,” Journal of Intelligent Transportation Systems: Technology, Planning, and Operations, vol. 11, no. 3, pp. 143-155 (2007); C.-Y Chan and B. Bougler, “Evaluation of cooperative roadside and vehicle-based data collection for assessing intersection conflicts,” in Proceedings of IEEE Intelligent Vehicles Symposium, pp. 165-170 (2005).
Adaptive cruise control systems that determine control inputs to control brake force and engine force of a vehicle based on, for example, distance between the vehicle and a vehicle traveling in front of the vehicle are also known. These adaptive cruise control systems do not take into account future traffic signal information to control vehicle velocity through a plurality of traffic signals based at least in part on the future traffic signal information.
U.S. Patent Application Publication No. 2003/0016143 discloses an intersection vehicle collision avoidance system that provides alerts to vehicle operators based on various conditions as the vehicle operators approach an intersection.
U.S. Pat. No. 6,989,766 discloses a smart traffic signal system in which traffic signal data is broadcast for receipt by vehicles traversing the roadways controlled by the traffic signals. The traffic signals can have the capability to broadcast their location, status, changing cycles and timing data. A receiving system in a vehicle is configured to receive the traffic signal data and provide to a user of the vehicle visual display information and/or audible information informing the user of a velocity range which, if followed, provides a speed for traveling through a traffic signal.
All of the foregoing patents and patent publications are hereby incorporated by reference for all purposes.
While various intelligent traffic signal systems and methods have been developed, no system or methodology has emerged that generally encompasses all of the desired characteristics as presented herein in accordance with exemplary embodiments of the present invention.